// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_MEDIA_SESSION_AUDIO_FOCUS_MANAGER_H_
#define CONTENT_BROWSER_MEDIA_SESSION_AUDIO_FOCUS_MANAGER_H_

#include <list>
#include <unordered_map>

#include "base/memory/singleton.h"
#include "content/common/content_export.h"
#include "content/public/browser/web_contents_observer.h"

namespace content {

class MediaSessionImpl;

class CONTENT_EXPORT AudioFocusManager {
public:
    enum class AudioFocusType {
        Gain,
        GainTransientMayDuck,
    };

    // Returns Chromium's internal AudioFocusManager.
    static AudioFocusManager* GetInstance();

    void RequestAudioFocus(MediaSessionImpl* media_session, AudioFocusType type);

    void AbandonAudioFocus(MediaSessionImpl* media_session);

private:
    friend struct base::DefaultSingletonTraits<AudioFocusManager>;
    friend class AudioFocusManagerTest;

    AudioFocusManager();
    ~AudioFocusManager();

    void MaybeRemoveFocusEntry(MediaSessionImpl* media_session);

    // Weak reference of managed MediaSessions. A MediaSession must abandon audio
    // foucs before its destruction.
    std::list<MediaSessionImpl*> audio_focus_stack_;
};

} // namespace content

#endif // CONTENT_BROWSER_MEDIA_SESSION_AUDIO_FOCUS_MANAGER_H_
